Finalize removal of `activity_bookmark_time`
There are still three occurrences of activity_bookmark_time
(which was removed in commit 496f7776:
grouprise/features/gestalten/models.py
69: for gestalt in queryset.order_by("activity_bookmark_time").prefetch_related(
grouprise/features/matrix_commander/commands.py
175: date_activity = gestalt.activity_bookmark_time.strftime(TIME_FORMAT)
grouprise/features/associations/querysets.py
124: qs = qs.filter(last_activity__gte=user.gestalt.activity_bookmark_time)
@robert: do you have ideas, how to fix/replace these?